For the beginning or even Intermediate Student of Photography there are the basic modes of every camera you must get familiar with, however, its easier to master ONE MODE at a time eventually ending up shooting ALL MANUAL!
#1 Fully Automatic! this one we not use at all, however in a pinch in a hurry so a shot won’t be missed its probably OK
#2 TV is Shutter Priority, This is when you set a desired shutter speed and let the camera automatically determine the other settings, This mode is especially necessary to stay within a particular Focal Length, lets say 200 MM and you really don’t want to shoot at less than 1/200 of second! You could get blurred images if shooting under 1/200 with a 200MM lens,
#3 AV is Aperture Priority, this is when you want to shoot a desired DOF (Depth of Field) and this would determine if the BG (background) is in focus or out of focus, AKA known as Shallow DOF
#4 M for Manual, Now your camera is complete control of YOU, you determine Shutter Speed, Aperture, and ISO, by changing the settings on all three, they are affected by the other and would change the image